1. Field of the Invention
This invention relates to a king pin/knuckle arm assembly for a steering mechanism and is particularly directed to a closed cell foam insert disposed between the king pin and knuckle arm.
2. Description of the Prior Art
Numerous kingpin knuckle arms assemblies exists in the prior art. U.S. Pat. No. 5,213,352 to Chalin discloses a kingpin steering axle assembly comprising an axle, knuckle arm, a king pin pivotally connected to the axle and knuckle arm and an upper cap with a grease fitting retaining the king pin within the knuckle arm. A thrust bearing is disposed between the king pin and the knuckle arm to reduce friction and wear. Each of U.S. Pat. Nos. 3,542,392; 3,441,288 and 2,916,295 disclose variations of conventional steering knuckle mechanisms. Each of the aforementioned U.S. patents are incorporated herein by reference.
The steering knuckle king pin arrangements of the prior art suffer from the drawback in that the king pin is allowed some degree of axial displacement. Such displacement relative to the knuckle arm causes a change in volume in air/grease volume between the kingpin and kingpin cap or bottom of the knuckle arm. These volume changes created negative and positive pressure fluctuations that act as a pumping mechanism to expel grease and ingest water and other contamination from the kingpin-to-knuckle sealing interface. The object of the present invention, therefore, is to alleviate the drawbacks of the prior art and prevent pressure fluctuations in the void space between the kingpin and kingpin cap and or bottom recess portion of the knuckle arm.